Why Does Concrete Crack?Aug 21, 18

Lets face it, in the greater Houston area, you've seen cracks in concrete. Although you may never have paid much attention to them unless your child was playing “don’t-step-on-a-crack-or-you’ll-break-your-mother’s-back".

When do we start paying attention to cracks in the concrete? When the cracks are on our own driveways, pool decks, sidewalks, or in the foundations of our homes.

Now that you know the cracks is there, you are probably wondering what to do and how it got there. You'll want to know what kind of crack it is, what caused it, and how to stop it. Well we are here to help you understand. Luckily as Charlie Puts says, we are just "one call away" (you sang it!).

What Type Of Crack Is This?

Cracks fall into two main categories: active or dormant. Active cracks visibly change direction, width, or depth over time. Dormant cracks, on the other hand, show no signs of change.

Both active and dormant cracks may require repair, because any type of cracked concrete is vulnerable to taking on moisture and thereby becoming damaged further. What may seem like a small, insignificant crack now could become a serious problem in the future.

Both active and dormant concrete cracks come in many shapes and forms. It’s helpful to understand the differences between the different crack types, because while some don’t pose serious risks, others could inflict major structural damage to your home or property.

The following are the crack types Leveled Concrete sees most often in our concrete repair work throughout Texas. The severity of each of these crack types is determined by its width, depth, and direction.

PLASTIC-SHRINKAGE CRACKS

What it looks like: These cracks run about halfway into the concrete. They’re usually short and unevenly distributed across the surface.

Why it happens: These cracks occur when concrete is curing. They happen when the surface dries too rapidly (generally due to an increased rate of evaporation), before the concrete has set. (it gets hot here, if the contractor didn't take precautions, this is common.)

Do I need to worry about it? Because this is a surface crack, more serious structural issues are generally not a problem. Typically, these cracks don’t impact your concrete’s durability.

MAP CRACKS

What it looks like: Map cracking looks like a road map. It consist of a series of thin, shallow cracks that run across the concrete’s surface.

Why it happens: This can also be caused by issues with the curing. Because this crack is only on the surface, it shows that the drying has occurred only at the surface level, constrained by underlying concrete that shrank less.

Do I need to worry about it? Again, because this is a surface crack, more serious structural issues are generally not a problem. These cracks generally don’t impact your concrete’s durability, either.

HAIRLINE CRACKS

What it looks like: Hairline cracks are very, very thin but can be quite deep

Why it happens: These occur when the concrete settles during the curing process.

Do I need to worry about it? Yes. Because they can be so deep, these cracks can lead to more damaging cracks after the concrete hardens. Obtain the opinion of a professional.

POP-OUTS

What it looks like: These are cone-shaped depressions in the surface of the concrete. Kind of like a bubble popped at the top of the concrete.

Why it happens: This happens when there is an especially absorbent piece of aggregate near the surface. The aggregate causes expansion and pops out of the concrete’s surface.

Do I need to worry about it? Typically, pop-outs don’t impact the concrete’s structural integrity. Whether you want to repair a pop-out will depend on its size and location.

SPALLING

What it looks like: Spalling refers to depressions in the surface that are linear along the length of a piece of rebar. The depressions are larger and deeper than those seen in scaling.

Why it happens: Spalling is caused by pressure rising from below the concrete’s surface. This most often occur when joints are not properly made, or if the rebar has corroded. Corrosion will create pressure as the rebar rusts, which pushes chunks of concrete away from each other and exposes the metal below the surface. This is a particularly severe form of spalling, as the corrosion accelerates when exposed to the elements.

Do I need to worry about it? It depends on the extent of the spalling. Does the spalling cause safety issues? Does its aesthetic appearance reduce the value of your property? Regardless, be aware that spalling is an active crack type, so it’s likely to continue.

OFFSET CRACKS

What it looks like: This type of crack occurs when the crack is higher on one side than on the other.

Why it happens: This happens most often because there is unevenness below the concrete, possibly from objects like tree roots, rebar, or old concrete.

Do I need to worry about it? Yes. Repairing these cracks is generally a good idea for safety reasons. They are often trip hazards.

How Do I Decide Whether I Should Get The Crack Fixed?

Now that you’re at least vaguely a concrete-crack identification expert, you may be wondering if certain cracks on your driveway, sidewalk, stairs, or elsewhere on your property may be problematic. As Houston's most highly rated trusted choice for concrete repair, Leveled Concrete would be happy to come take a look and share our professional judgment. Schedule a free onsite visit and we’ll help you determine whether repair is the right option for your crack. Because again – that crack isn’t about to tell you anything. You might as well talk to us!